Study on uniform parameters characterizing the crack-tip constraint effect of fracture toughness

Abstract

Abstract The plastic zone of crack-tip is connected with the constraint level inherently. Based on this, a unified crack-tip constraint parameter Cp was proposed. And through finite element analysis (FEA), the Cp can be recognized as a characteristic parameter in the description of equivalent stress fields. Moreover, the ductile material SA-508 steel was used to test the effectiveness of Cp as a uniform parameter, three different configurations (CT, SENB, Mini-SENB) of specimens with different crack lengths and thicknesses were employed to distinguish the effects of constraints on ductile fracture toughness. The result showed that clear linear relationship between the Cp and J0.2BL is shown for all specimens with different dimensions, which can be used to determine constraint-dependent fracture toughness for the specimens or flaw components of SA-508 steel, regardless of in-plane or out-of-plane constraint or both.